Gas making process



v Aug. 22, 1,933. A. JoHNsoN 1,923,540

GAS MAKING PROCESS Filed June 19, 1929 4 Sheets-Sheet. l

Aug. 22, 1933 A. JOHNSON 1,923,540

GAS MAKING PROCES S.

Filed June 19, 1929 4 Sheets-Sheet 2 NVNTOR ALFRED doHNsON hig ATTORNEYAug. 22, 1933. A, JOHNSON GAS MAKING PRocEss Filed June 19, 1929 4Sheets-Sheet 3 SWW/who@ ALFRED JOHNSON 3613 his Aug. 22, 1933. A,JQHNSQN v 1,923,540

GAS MAKING PROCES S Filed June 19, 1929 4 Shets-Sheet 4 @da i [O50 IIOOOO |300 |400 (500 |600 IIOO mEAN MeTAL TEMPERATURE-"F Swix/whom ALFREDJOHNSON www Patented Aug. 22, 1933 1,923,540 Y GAS MAKING PROCESS AlfredJohnson, West Brighton, Y., assigner to Combustion UtilitiesCorporation,

New

York, N. Y., a Corporation of Maine Application June 19, 1929. serialNo. 372,112

19 claims. (o1. iii-202) The present invention relates to processes `andapparatus for the distillation and gasification of carbonaceous fuels,and more especially it concerns a process and apparatus for theconcurrent carbonization in place of high volatile bituminous fuels suchas coal and the gasification of the residual coke in a semi-continuoussuccession 0I" operations in an integral unit having a car`1 bonizationzone. of limited annularcross section positioned inthe upper end of'agas generator casing directly above the fuel bed of the latter.

YThe advantages to be gained by the carboni- Zaton of fuels in thinlayers is now well known. It has been determined that the rate offuelcarn bonization by external heatingwparticularly when employingtemperatures within the low temperature carbonization range,-isrsubstantially inversely proportional to the square of the thickness ofthe fuel layer being carbonized;for example a fuel layer y3" inthickness, when heated to a given temperature from each of the sides ofthe said layer, will carbonize in onequarter the time required undersimilar conditions for carbonizing a 6" layer of fuel.

Carbonizing processes as at present coinrnonly performed in verticalretorts or the like in which the coal is progressively fed downwardthrough the retorts have not proven suitable for carbonizing thin layersof fuel, due to the mechanical difficulties, both in moving such thinlayers of material through the carbonizing chambers of such retorts andin discharging the coked product. The material tends to form aplasticsticky mass at an intermediate stage of the carbonization and toadhere to the walls of the ccking chamber.

Accordingly, it has heretofore been standard practice to carbonize arelativelythickv column of fuel; and this is essentially true where thedistillation apparatus has been directly associated with an apparatusfor the complete gasification of the carbonized fuel. It is preferablethat the fuel be fully carbonized before being r moved onto thegenerator `fuel bed. Because however of the very slow rates at whichthiol: layers of solid fuel can be heat-treated 'to yield a properlycarbonized product, it has been necesu sary in the past either toundertreat the fuel so Y that it was not completely carbonized, oralternatively to seriously reduce the carbonizing capacity of theinstallation by prolonging the carbonizinfT time of the charge.

Among the principal objects of the presentinvention are to provide in animproved manner for the rapid uniform carbonization of a column heatedindirectly While held in place; to provide for the carbonization of coalin thin, annular" layers on water gas and/or` producer cycle.`r Theseand other important objects will be clearly indicated in the course ofthe following de` scription, `and in the appended claims.

Broadly considered the present invention involves the carbonization of asolid fuel such as bituminous coal or lignite in elongated retorts ofannular 'cross section, ya plurality of whichv are suspended in avertically-disposed heat-insulated gas generator4 directly above thefuel bed of the Y latter. `The gas generator may be either a Water gasgenerator or aproducer gas generator. The( carbonization of the fueliseffected within the annularl space confined between the concentricYinner and outer vvalls of each of the. said annular retorts. Heat for,the carbonization is trans`' mitted to the said walls of each retort, inpart by radiation from the incandescent fuel bed and in part by means ofthe sensible and potential heat in the gaseous products passing incontact v.

with the said walls of the annular retorts, as will` be morespecifically `described hereinafter. Y

Therate of carbonization of the fuel has beenV greatlyV acceleratedaccording to the presentin- -vention by exposing a relatively thinannular column of the fuel to carbonizing heat applied preferablysimultaneously to ,two opposite sides thereof. In practice the thicknessofthe fuel column annulus is less than 5 and is preferably about 3".

As rapidly as the annular column of fuel is carbonized, the resultantcoke is discharged di.- rectly onto the fuel bed of lthe gas generatorby suitable means. The coke is thenr gasiiied in the said generator onstandard water gas cycle or producer gas cycle, or upon a slightlymodified series of cycles, the preferred modifications of which arehereinafter set forth.

To offset or neutralize the effect of the uneven vertical distributionof heat along the respective walls of the annular vertically mountedretorts during the producer gas and water gas cycles by heat transferredfrom the hot gases7 the invention comprises a further stage ofindirectly heating the annular column of fuel being carbonized 1y meansof highly superheated steam passedin' downrun Contact with either theinner or the outer walls of each retort, but preferably with both ofthem, the said superheated steam transferring portions of its heatduring such passage to the upper relatively cooler end of each of theretorts while Yitself being sufficiently cooled in its downward passage,so that as vit moves past the lower portions of the respective retortswhich are constantly exposed to the heat directly radiated and thatotherwise conveyed from the incandescent fuel bed, the stream acts toabsorb heat from the said lower portions so as to lower the temperatureof the latter. In this manner the downrun steam functions both as acarbonizing agency and as a means for equalizing theretort walltemperatures at' the respective end portions thereof. This tends topreserve the life of the retorts. Preferably potential heat recoveredfrom the waste blast gases from an earlier cycle is employed forsuperheating the steam employed in the last named or downrun steamcycle.

, Undesirable variations in temperature between the lower and upper'endsof the carbonizing retorts also can be preventedin large part kby thesuccessive addition of secondary air around the outer Walls ofV theretorts at suitable points spaced vertically ofthe Vretorts. The amountsof such air preferably` areso controlled asto efectthe combustion ofpredetermined proportions of the gases issuing lfrom the fuel bed atdifferent elevations lengthwise of thegenerator housing. This furtherincreases the temperature of the hot gases contacting with the retort,Walls and particularly those portions of the latter which are moreremote from the generator fuel bed'.

, To further facilitate the uniform carbonization of the fuel where thesaid vertical tempera- ,ture gradient exists, the outer of theconcentric walls of each retort may be slightly tapered outwardly in adownward direction so that the thickness of thercoal layer in the lowerportion of the annular carbonizng zone, which is subjected to relativelyhigher temperatures than the fuel in the upper portion thereof, isthicker in annular cross section than the latter. The relative thicknessof the fuel layerat the respective upper andV lower portions of the fuelcolumn is 50. preferably adjusted in accordance with the above 55 l theannular fuel column, the inner retort wall is adapted to be filled withrefractory materials such as checker brick, Raschig rings, or the likewhich act to absorb heat from the hot gases passing alongV in contactwith the inner wall of the retort, and to transfer suchheatr to thelayer of fuel being carbonized. This refractory material is veryeflicient as a heat-absorbing and transfer means when employed in themanner indicated, as shown by the fact that the portion of thecarbonization effected by transfer of heat vfrom the inside surface ofthe annular fuel layer ferred through the inner Wall of the annularretort when the inner retort member is packed with this refractorymaterial.

In carrying out the process, the available heat in the hot gasesemployed in heating the respecerably balanced in accordance with thetotal area Referring now to the accompanying drawings v which show apreferred form of the apparatus exemplifying the present invention:-

Fig. 1 is a vertical cross sectional viewof a preferred form of acarbonizing and gasification apparatus, parts'thereof being broken away;

Fig. 2 is an elevational View on a somewhat larger scale, showing theupper end of the generator housing and certain of the parts associatedtherewith, portions thereof being cut away, and other portions beingshown in section Fig. 3 is a horizontalsection of the apparatus takenalong the line 3-3 of Fig. 2 looking in the direction of the arrows;

Y Fig. 4 is a chart which indicates the relationship between thecarbonizing capacity of the retort and the thickness of the layer offuel beingV carbonized within the scope of the present invention, at'various indicated temperatures within the preferred carbonization range;and

Fig. 5 is a chart that indicates the relationship existingbetween thecarbcnizing capacity of a retort and the temperature at which thecarbonization is carried out, for definite thicknesses of fuel layers.

"In the drawings 10 designates a vertically arranged, gas-generatingapparatus suitably lined with refractory material throughout andprovided with a cylindrical side Wall 11, a base or bottom member 12,and a closed top 14. VThe side wall 11 is suitably constricted at anintermediate portion thereof to form a lower portion 15 of reduced crosssection. A grate 17 of usual construction is positioned in the bottom ofthe genbe substituted for that shown.

For introducing 'air under pressure into the lower portion of thegenerator casing,'av pipe 2l controlled by valve 23 extends through theside of the generator below the grate 17 and is connected with asuitable source of air under pressure.

Supported from the top member 14 of the gas generator and disposed incircular arrangement at uniformly-spaced intervals are a plurality ofdepending, elongated hollow tubular retort members 29 of steel or othersuitable heat-resistant metal or metal alloy such as hybnickel.

their enlarged lower ends positioned near but somewhat above theconstricted portion in the generator casing.

In a typical installation, there is approximately a 1" difference incross-sectional diameter of the said member for each 8 feet of thelength thereof. l

The upper end of each of the retort members 29 extends through thegenerator top 14 and to a point substantially thereabove, and each isprovided with a flanged cover'plate 3l having a relatively large,centrally-disposed aperture 33 therein, and having a second aperture 35located therein near the peripheral margin of the cover plate 3l.

A tubular metal curtain 37 is mounted on the under surface of each plate31 .concentric with and surrounding the aperture 33, and it extendsdownward within the retort member 29 to a point The` depending tubularmembers 29 preferably taper,y outwardly in-a downward direction, andhave VV grate, as for example, a non-clinkering grate, mayv dependingcurtain members 39, 39 extendsradially from the outer edge of thecurtain 37 within each retort to the adjacent inner retort wall on.

respective sides oilthe aperture 35 to provide a passageway leading fromthe interior of theretort to the said aperture. Other radial members 40,40 divide the remainder of the annular space between the curtain 37 andthe retort 29 into a plurality of parts.

Each of the tubular retort members 29 has disposed therein andconcentric therewith a generally cylindrical hollow inner retort member41 having the ends extending beyond the ends of the member 29. Each ofthe inner retort members 41 is made of suitableresistant metal or alloysuch as hybnickel, and is adapted for limited vertical movementlongitudinally of the concentric member 29.

The lower margin of each of the members 41 is flared or bevelledoutwardly and extends laterally beyond the bottom margin of theconcentric retort member 29,-the arrangement `being such that uponmoving the inner member 41 vertically upward the said flared lower endof the lat-- ter engages the bottom of the member 29 and forms asubstantially gas-tight seal for 4bottom of the annular chamber defined.between the pair of concentric retort members 29, 4l. The constructionof the concentric retorts 29, 41 is preferably such that the annularfuel receiving space deiined therebetween is less than 5f ineffectiveiannular width, and the preferred optimum width of this annularspace is approximate- 1y 3H.

Each `of the retort members 41 is substantially constricted adjacent theupper end of the retort member 29 to form an upper-end valve portion 45of greatly reduced cross section. The said `portion 45 extendsvertically upward through the aperture 33 in the cover plate 31, and itsextreme upper end is closed rby a cap 46. The upper portion of eachmember 41 is operatively secured to a housing member 47 of acushioningor shock-absorbing device, a second member 49 of the saiddevice being adjustably secured to the piston 51 of a hydraulic cylinder53 which is utilized for raising and lowering the retort member 4l. Thesaid cylinder is mounted upon a suitable superstructure 55 supportedupon the top of the generator by the column 56..

operatively interposed betweenthe members 47. 49 of each cushioningdevice are a pair of con-k centrically disposed compression springs 57,53, which are so arranged as to resist the tendency toward downwardmovement o the respective inner retort 41 under the influence of its ownweight and that of the fuel being carbonized.

.An elongated slot or opening 59 is provided in the upper constrictedportion of each of the inner retorts 41 at a point above the top plate3l.. A hollow T-shaped casting 61 surrounds the portion of the member 41having the said slot 59 therein,V

and provides an annular chamber adapted to be in free communication withthe interior of the member 41 only when the latter is in its uppermostposition. The interior ofthe member 41 is adapted to be in communicationwith 4the upper end of the annular fuel space when the former is in itslowermost position. A stufling box associated with each top plate 31furnishes a gas-tight seal between the interior of casting 61 and theannular fuel space and comprises a housing 68 `belt 117.

in which is mounted a metal collar or seal ring 69 provided lwith aplurality of grooves in itsinner peripheral surface, each adapted toaccommodate a contracting piston ring 71 for cooperation with theadjacent surface of the inner retort member 4l.. A set screw or the like`v73` cooperates with the housing 68 to prevent movement of the collar69 with respect to the -inner retort member.

The upper end of the T-shapedcasting 61 has an opening therein throughwhich the constricted upper end portion 450i the inner retort member isadapted to extend. A stuffing box 75 of usual construction is mountedupon the casting 61 aroundvthe portion 45 `and seals the interior of thecasting :from the atmosphere. The said interior of castingl is connectedby pipe `63 controlled by valve 64, to a collecting main or junction box65 centrally located on the top 14 of the generator.

For charging fuel to be carbonized into the annular space between eachpair of concentric tubular retort members 29, 41, a fuel charging hopper91 is centrally mounted upon the superstructure 55. The hopper 91 isprovided with a gas tight closureV member 93 and is divided intothree-superposed compartments 95, 97, 99, by a pair of vertically-spacedfunnel shaped partitions 101, 103, v

jacent the generator top to form fuel feedv pipes. 111, 111, which openinto the upper end of one' of the annular retort spaces through openingsin opposite sides of the cover plate 31 between the metal curtain 37 andthe outer retort Wall` 29.

Forconveying fuel from the storage compartment 95 into the compartment97 at a uniform rate, a positive feed mechanism is provided comprising ascrew conveyor 113 mounted `upon'the upper portionv of member 101 anddriven from a suitable source of power through pulley 115 and Therfunnel shaped member 103 has a central opening located directly abovethe midportion or the bottom of the hopper 91.

The upper closure member 93 of the'hopper is controlled by a hydrauliccylinder 127 functioning inthe manner shown, through a bell crank Theupper portion of the generator casing 10 is connected by means of thepassageway 131 with the upper portion of a regenerator 133 of'well knowntype provided with checkerwork 135 of a heat refractory material, thesaid passageway 131 being provided with a cut-orf valve 132. vThe lowerend or the saidregenerator is connected with Aa wasteheat boiler oreconomizer 137 by means of a passageway 139 having therein a shutolfvalve 145.v The gas outlet end of the economizer communicates with astack 141 provided with a hydraulically-operated draft regulator orclosure 143. The lower end of the regenerator is also directly connectedwith the stack 141 by means of pipe 147 having valve 149 therein, for

cy-passing the economizer 137 when desired.

The upper end of the regenerator 133 is con-1 nected by means of a pipe151, controlled by a hydraulic valve 153 and a checkvalve 154, with 183.valve-controlled pipes 185,187, 189, with each of a plurality ofvertically-spaced bustle-pipes `like present in such vapors.

coolers and scrubbers and to a .lean gas holder (not shown). A hydraulicvalve 157 and a check valve 158 are providedin the pipe` 155 between thepoint at which the pipe 151 opens into it and the said lean gas coolers.

For conducting lean gas from the base of the generatorV casing below thegrate to suitable gas holders, a gas tuyer 159 controlled by valve 165has one end thereof opening into pipe 21 at a point between the saidcasing and the valve 23. The other end of the tuyer 159 is connectedwiththe pipe 155 at a point therein between the valve 157 and the lean gascoolers. A branch pipe 161 controlled by valve 163 connects the stackl141 with the pipe 159.

For introducing steam into the apparatus, a pipe 167 controlled by valve173 has one end thereof connected to a suitable source of steam underpressure,-the other end of the pipe 167 opening into the lower end ofthe regenerator 133. A branch line 169 controlled by valve 175 connectsthe steam pipe 167 with that portion of pipe' 21 between the generator10 and the valve 23. f For distributing secondary air into the gener--ator casing immediately above the fuel bed and atV vertically-spacedpoints in the generator casing adjacent the annular retorts 29,-andalso.

for conducting air for combustion to the upper end of the regenerator133,-a branch conduit v177 controlled by valve l179 leads from the airpipe 21 into the upper end of the said regenerator. An intermediatepoint in the line 177 is connected by pipe 181 with avertically-disposed manifold The latter is connected respectively by197, 199, 201, surrounding the generator casing. Each of thesaidbustle-pipes has leading therefrom a plurality of radially disposedvalved pipes 203 provided with suitable air injecting nozzles 205extending through the generator wall, the arrangement preferably beingsuch that the lower set of nozzles extends through the constricted lowerportion of the generator casing immediately above the fuel bedtherein,-an intermediate set of nozzles extends into the casing 10 atapproximately the same elevation as the lower ends of the retorts 29,and another set of nozzles extends through the casing at approximatelythe'same elevation as the mid-portion of the retorts 29.

For removing the gases and vapors as they are formed in the annularcarbonizing space between the respective pairs of retort members 29, 41,during the carbonization of the fuel therein, each cover plate 31 hasmounted thereon a header or casting 207, connecting 'the said annularfuel space through a valved pipe 209 with a bustlepipe 211. The latteris connected by pipe 213 with a set of primary rich-gas coolers andscrubbers and therethrough with a rich-gas holder (not shown). A pipe215 extends-into the header 207 for use in injecting water into thevapors flowing therethrough for condensing tar and the A steam pipe 21'?extends into each of the fuel feed lines 107 immediately below the valve109 therein; and a steam:

37 where tarand the like might be condensed` and deposited.

For carburetting the bluev gas made in oneof the cycles of the processaccording to one modi-y Va preferred application of the process in theproduction of a modified blue gas. Assuming that the generator isprovided vwith an already ignited fuel bed of coke or the like asproduced in accordance with the present invention, a charge of fuel tobe carbonized filling the annular space between the inner and the outerretort members of each pair thereof, a blast of air is introducedthrough pipe 21 below the grate 17 and is passed through the burningfuel in the base of the generator,r the said air being mixed if desiredwith a relatively small amount of steam for temperature controlpurposes. The air blast is preferably continued for approximately twominutes, the fuel in the fuel bed becoming incandescent, and producergas being formed. The resultant products of primary blast normally issuefrom the upper surface of the fuel bed at about 1600 F. Secondary air isalso admitted to the generator just above the fuel bed during thisperiod of the blast'for the purpose of burning a partof the gases asthey leave the fuel bed to assist in raising the temperature of the saidgases to approximately 1900o F., this being the preferred temperaturefor the gases employed in heating the refractory material positionedwithin the inner one of each pair of concentric retort members. Theproducts of the primary air blast are then divided, part thereof movingupward within the refractory-filled inner members and vbeing withdrawnthrough the respective slots 59 in the upper end thereof and beingconducted away through the junction box and lean gas pipe 155. Part ofthis said lean gas may be introduced into the upper end of theregenerator 133 through line 151 where it is burned in the presence ofair introduced through the pipe 177 for thepurpose of heating thechecker work in the regenerator. The resultant products of combustion ofthis portion of the lean gas are conducted downwardly through theregenerator and from there they may be led throughthe waste heat boilerand through the stack to the atmosphere. The balance of the lean gasflowing in pipe 155 is conducted through valve 157 through a lean gascooler to a lean gas holder orto a common mixing holder.

Another portion of the gases leaving the generator fuel bed passupwardly around the outer retort member 29, giving up their heat throughv the said retort walls to the fuel being carbonized.

These cooled gases after such heat exchange flow from the generatorthrough passageway 131 into the upper part of the regenerator where theymixl determined amounts of air are introduced into' and mixed therewithat a plurality of points spaced vertically of the generator, for thepur- `if and as desired into two portions.

pose of maintainingthe Vvarious portions of the outer retort walls atthe desired temperature and for uniformly carbonizing the fuel.

At this point in the process the air blast is discontinued, valves 23,191, 193, 195, 143, and 179 being closed, and the uprun make cycle isbegun. Steam is admitted into the lower part of the generator beneaththe grate by opening valve 175 in the steam line 169, steam valve 173being closed. The blue gas formed by the steam in passing upward throughthe incandescent fuel bed is again divided, as in the previous or airblast cycle, a predetermined part of the hot blue gas being conductedalong each refractoryfilled inner retort member to assist in supplyingheat thereto for the carbonization of the annular layer of material.This part of the blue gas thereafter passes through the ports 59 in theupper end of the inner retort members and through the lean gasbustle-pipe and tuyer 155 to the primary lean gas coolers and thence tostorage. It may be stored in aV separate holder from the producer gaspreviously conducted through the pipe 155, or it may be mixed with theportion of the primary blast gases that were taken to storage during thefirst cycle of the operation. A second predetermined portion of the bluegas generated in the second or uprun make cycle passes upward throughthe generator in contact with the external retort walls and isthereafter conducted from the generator through the passage 131 and thepipe 151 to the tuyer 155 where it mixes with Vthe blue gas passingupwardly through the inner retort member and is conducted therewiththrough the lean gas coolers to storage. i

During this uprun make cycle the fuel bed is rapidly cooled and theproportion of the heat radiated to theretort members from theincandescent fuel bed falls oifappreciably. In order to maintain asatisfactory uniformvcoking temperature vertically! along the fuelcolumn during this cycle, sufficient air preferably is introducedthrough the pipes 203 to burn predetermined portions of the said bluegas so as to maintain the hot gases contacting with the inner andouterwalls of the annular fuel column at the-desired temperature during suchcontact. upruncycle has been in operation forv the desired length `oftime, it is terminated by closing the steam Valve 175, the variousvalves 191, 193, 195 in the air line, and valve 157. f i

A downrun cycle is now started during whic steam is admitted throughline 167 into the lower portion of the regenerator, the valves`145-and149 respectively connecting the bottom of the regenerator with the wasteheat boiler and with the stack being closed, and the valve 165 inconduit 159 being opened. The steam is drawn up-Y wardly through theregenerator, at the same time being highly superheated by heattransferred thereto from the highly heated checker work. The thussuperheated steam is thereafter divided One rof `the said portionspasses through the passageway 131 into the upper part of the generatorcasing,and descends therein, in contact with the walls of the outerretort members 29. The superheated steam, being at ahighertemperaturethan that of the upper portion of the said retorts gives up heat to thelatter, and is itself cooled and again absorbs` heat from the lowerportions of the retorts adjacent the hot generator fuel bed` in a mannerto oset the heating of the lower portions of the respective retortmembers to `of the pairs of concentric retort members.

vthrough the said members, giving up its sensible heat to the refractoryfillings thereof, and it gasholder or a common storage holder.

.tionsas a'support for the fuel column when it is After the f *cessionin such manner that the carbonization of the Vcontentsof one retort atatime is com- .substantially constant level -and insures a uni- `fro1nflowing through` the space lying between higher temperatures than theupper `portions thereof by the heat radiated from the fuelfbed and bythe sensible and potential heat of the gases formed in. the two previouscycles. `The remaining portion of the superheated steam passing upwardlythrough the regenerator, is conducted 80 throughl pipes 1571 and 155,the junction box and the slots 59, and into the inner one Vofi each Thesaid superheated steam then flows downwardly thereafter passes throughthe hot fuel bed 220. The blue gas thus formed by reaction of this steamwith the highly heated fuel is conducted ,through conduit 159 to theprimary lean gas coolers and thence to storage. f Y

The down run cycle preferably lasts for about one minute and a quarter,after which a short uprun' of purge steam is effected preparatory toagain starting the air blast of another cycle. The purge steam :andgasescarried thereby are preferably conducted'either to lean gas holdersor exhausted to the atmosphere..

The distillation products obtained during the carbonization of the fuelcontaining for example various liquefiable and gaseous hydrocarbons,coal gas, tar, water vapor, ammonia 'and the like, are withdrawncontinuously from the upper part of the annulalr fuel space during eachof the above mentioned cycles and pass through header 207, bustle pipe211, and the pipe 213 to a set of primary rich gas coolers preferablyunder subatmospheric pressure, and thence to a rich These gas-.makingcycles are continuously repeated in the order given until the.carbonization of the fuel in at least one of the retorts has beencompleted. Thereupon the inner retort member il is moved downward byoperating the hydraulic cylinder controlling it, and the carbonizedmaterial is discharged by gravity downwardly onto the generator fuelbed. The flared portion of the bottom margin .of the inner retort memberfuncin its upmost position, and it also vacts as a valve to preventsubstantial proportions of the heating gases such as producer gas andthe like from passing to the 'fuel column and escaping into the rich gasofftake during the carbonization period. When the inner retort member isin its lowered position, the flared bottom thereof assists in breakingup large lumps of coke falling upon it duringthe discharging process. y

The retort pairs are preferably filled in sucpleted,` and so that thesuccessive dumping of the carbonized fuel fromthe rvarious retorts ontothe generator fuel bed maintains the latter at a 3a form distribution ofcarbonized fuel on the surface of the fuel bed. `The discharging of thecoke material onto the generator fuel bed is preferably done during the.downrun cycle, and any fine dust and the like escaping Vinto thegeneratoris drawn into the fuel bed 229 and does not interfere with theprocess.

Lean producer gas and the like are prevented 140 the ytwovconcentric-retort members during the. time that the inner member is lowered fordischarge ofjcokadue. to the'fact that the slot 59 then is positionedbelow the seal ring 69. During this time valve' 209 is vclosed'topreventthe pas- 150 sage of 4lean gas into the rich gas'bustle-pipe211'.

-When the'inner retort memberis again raised -top of the'y hopper beingclosed and the proper feed vali/e109 being open.

Preferably the compartment holds just suflicient fuel to properly chargeone of the said annular retort assemblies. The conveyor 113 permits auniform, determinate rate of charging fuel to each of the said retortassemblies, regardless of the amount of fuel in thehopper.

.The fuel charging may be discontinued at any stage by stoppingwtheconveyor-.113.V A limited downward flow of steam through the fuelcharging pipes 107 into the retort-offsets any tendency for distillationgases to collect in these pipes. The current of steam introduced intothe upper portion of each retort between the inner retort member 41 andthe metal curtain 37 preventsl the accumulation in thel space ofdistillation gases which might deposit therein objectionable materialssuch as tar.

According to a modification of the' process in which a carburettedcombustible gas is produced, the uprun make cycle is so controlled thatthe gas passing upward through the generator is at least lin large partconducted into the regenerator by properly setting or closing .thevalves-157 and 158, and opening the Valves 153 and 154, the said gasesAthen being conducted downward through the highly heated checkerwork inthe regenerator. Simultaneously a spray of suitable carburetting fluidsuch as a hydrocarbon oilor the like is introduced into the upperportion of the regenerator and if necessary is vaporizedand fixed at thetemperatures existing therein. The enriched blue gas is conducted fromthe lower end of the regenerator direct to the pipe 141 and, throughbranchr pipes 161 and 159, to suitable gas coolers and scrubbers and`then to storage,-the stack Valve 143 being closed. The economizer ispreferably bypassed to avoid the possibility of tar and the likecondensing in the ilues thereof. In like manner the last portion of thehot 1 producer gases formed in `the generator Vduring the blast cyclemay be carburetted by spraying a carburetting fluid into that portionthereof which is passed downward` through ythe highly heated checkerworkin the regenerator.V The introduction ofair to the regenerator throughthe air pipe 177 isvpreferably discontinuedprior to the introductionofthe carburetting fluid intothe said gases.

Instead of conducting all of the gases formed in the generator 10 duringtheA uprun make cycle through the regenerator, which yhere acts as acarburetor, ak portion or all of the gases passing through the innerretort members of each pair may be conducted direct to lean gas coolersand to storage with orfwithout portions of the .gases leaving thegenerator vthrough the passageway y 131, by suitable adjustment of thecheck valves y 154 and 158. v Y Y Although boththe inner and the outerretort members of each concentric pair are preferably fabricated fromthe same kind of heat resistant Vmetal,`it is -within the scope of thepresent Yin- -vention 'to make the inner retorts of different metal oralloy than that of which the outer retorts are made, so that they willexhibit different physical characteristics under the conditions of use.unbalanced elongation ofthe inner retort members underthe effect oftheir own weight at the high temperatures'employed, and to properlymaintain a substantially gastight seal between the lower ends of theinner and outer retorts, the

kextremeaupper end of the inner retort may be threaded'externally forcooperation with threads formed "upon the interior. of the lower end bfthe housing member 47. Other similar means for L accomplishing the vsameresult may be `employed if desired. For example, the flared bottom ofthe -inner retort of each pair may be separable from the tubular portionof such inner retort and may be adapted for adjustment longitudinallythereof. The compression springs 57 and 58 permit the raisingandilowering of thev inner retort membed `without `unduejarring and,injury to the apparatus. Y

It will vbe obvious that other methods of charging coal into theretort'may be substitutedfor that specifically shown and described. Itis also within the spirit of the lpresent'inventionto makey the outerretort member cylindrical while ern- -ploying a reverse taper on theinner retort member so that the sidesof the latter slope inwardly in adownward direction; or if preferred`A both inner andouter retort membersmay be slightly tapered.

By employing a cylindrical inner retort member, and providing the outerretort with an'outwardand downward taper, it is possible to vary thethickness of thefannular fuel layer to compensate for theusual-.vertical temperature gradient along `the retort walls, especiallyin instances where the said gradient has not been substantiallyeliminated by the combustion of. effective amounts of secondary air asalready described. In this way itis possible toappreciably increase thecarbonization capacity of retorts of the type here shown .and describedat approximately no additional cost.

The relative proportion of the` carbonizing heat `distributed along therespective surface of the vinner retort and the outer retort wall may becontrolled byysuitable vacuum-producing means 4arranged in the lean gasofftake line from either of the said retort members or by pressurecontrol ow involving kthe use of regulating valves hereinbeforementioned. l

apparatus construction in which a group of four uniformly spacedcarbonizing retorts is supported in the upper part of a gas generatorhousing hasfprove'n to besvery efcient and gives a very high carbonizingcapacity per unit of time per square foot of metal heating surfaceemployed. The process is preferably carried out with effective `retorttemperatures of from 1050 F. to 1500 F.

At temperatures much in excess of 15o0 F., while i the rate ofcarbonization is accelerated, there is a tendency toward cracking of thetar vapors,

'-which'interferes with the production'of primary tar andv reduces thetar residue credit, both from theA point of yield and quality. On theother hand at temperatures substantially below 1050 F., the carbonizingcapacity of the assembly is materially reduced, when usingthe'above-mentioned preferred thickness of coal or a thicker layerthereof, until a point is reached at which the number `of retortsrequired in order to permit the Inordery therefore to'compensate for anynous and the non-luminous or obscure radiationsfrom the incandescentgenerator fuel bed; and the area of that portion of the tubular retortsurface lwhich is exposed directly to such radiated heat is preferablythe maximum which is consistent with the maintenance of a suitably thinfuel layer in the carbonizing zone.

Fig. 4 clearly illustrates the rapidly increasing rate at which fuel iscarbonized when exposed to heat in the low temperature carbonizationrange, in layers 5" in thickness or less. The particular values fortemperatures of 1050*F. to 1400o F. and 1500" 1'". are shown. Ordinarilyin carbonizing fuel in annular layers over a water gas generator,certain diiiiculties are encountered where fuel layers of over 5" inthickness are employed, due to the excessive retort space required tocarbonize the necessary amount of fuel 'to serve the generator fuel bed,and to the resultant excessive cost of the apparatus assembly.

Fig. 5 illustrates the effect upon the carbonization capacity of aretort assembly due to varying the carbonization temperatures employed.rIhis effect is separately indicated for fuel layers respectively 3 and5" in mean thickness, between temperatures of l05 and 1800" F. However,at temperatures below l050 F. the carbonization capacity of the retorts,when using the optimum thickness of coal layer, -3--, is reduced to apoint wherethe number of retorts required in a self-contained gasgenerator set is excessive and imposes objectionable structurallimitations.

Among the important features of the present invention is the flexibilityof control which it permits of the B. t. u. value of the gases formed bythe gasification of fuel. In addition to the coal gas produced by thefuel distillation the gases produced in the generator in each cycle ofthe process may be collected separately or the said gases or any desiredportions thereof may be mixed to give a gas of the desired B. t. u.value. Moreover the heating value of these gases can be increased asdesired by carburetting selected portions of the gases passing from thegenerator as previously described. Predetermined portions of the gasesare preferably burned in the upper portion of the 'generator andin theregenerator, and the resultant products of combustion, or part thereof,may be mixed with the unburned portions of the gases and carried tostorage.

By the use of my invention as hereinbefore described I am able to effectthe various objects thereof and to provide for the efficient concurrentcarbonization and gasification of bituminous fuel and the like in aserni-continuous succession of operations, at the same time recovering ahigh B. t. u. coal gas and a second combustible gas mixture ofdeterminate B. t. u. value, together with primary tar, ammoniacalliquor, and the like. The invention is susceptible of modificationwithlin the scope of the appended claims.

I claim: l. The process of producing a combustible gas and concurrentlycarbonizing fuel in relatively thin stationary layers which comprisespassing a fluid through an incandescent fuel bed and concurrentlypassing the resultant highly-heated least a portion of the heat forcarbonizing the said fuel. f

2. The process of concurrently producing coinl bustible gas andcarbonizing fuel in thin layers which comprises passing air through anincandescent fuel bed, passing the resultant highlyheated blast gases'along and in indirect heat exchange relationship with a column of fuelarranged in a thin layer above the said fuel bed, thereafter passingsteam through the said fuel bed and then passing the resultant water gasthus formed longitudinally of and in indirect heat ex'- change relationwith the said column of fuel in. the same direction'with respecttheretoras that steam and passing the superheated steam along the fuelcolumn in indirect heat exchange' rela tion therewith, the direction ofl flow of the Ysaid superheatedsteam along the fuel column being in adirection opposite to that of the previous flow of the blast gases andthe water gas, and recovering the various combustible gases produced. 3.The process of distilling and gasifying solid fuel which, when carriedout ina water gas generator having one or more annular retorts suspendedwithin the upper portion thereof, com

prises the steps of heating a column of the fuel to be carbonized whiledisposed in a thin layer within a retort, by meansof hot gases moving'in indirect heat exchange relation with the said column around and onall sides of theretort, and

supplying controlled amounts of secondary air at predeterminedpointslengthwise of the said retort and adjacent vthe fuel columntherein in such manner as to `control the temperature gradient in thecolumn of fuel irrespective of the relative distance of each portion ofthe column from the source of the hot gases.`

4. rhe'process for distilling and gasifying solid umn being heatedindirectly fromV points` on opposite sides of the thin layer to producea higher temperature at the lower portion of .the fuel column than atthe upper portion thereof, and subsequently flowing hot gases along thesaid column downwardly from a point adjacent the upper endv thereof toequalize the temperature existing atV the two ends of the column andprovide for a uniform carbonization of the fuel.

5. In the semi-continuous process for distilling solid fuel in a columnof thin annular crosssection and forv gasifying the carbonized productby means of heat recovered from a combustible gasmaking cycle, appliedindirectly through inner and outer walls enclosing a carbonizing zone,the step of controlling the distribution of heat tothe respectivesurfaces of the annular layer to control the relative proportion ofthecarbonization effected atthe respective inner and outer surfaces of theannular column.

e. In the semi-continuous process for distilling and gasifying Asolidfuel, the step of applying` carbonizing heat to the solid fuel in anenclosed column of thin annular cross section by hot gases movingupwardly along on both the inside and outside of the annular column outof contact with the fuel, and controlling the thickness of the fuellayer to provide a greater thickness thereof sate for the effect of thehigher temperature of- .the said gases at their point of first contactwith the column, thereby facilitating a uniform time Yof carbonizationof the fuel throughout thelength vofthe column.

7. The semi-continuous process for concurrentlycarbonizing nely dividedfuel in an elongated column of relatively thin annular cross sec-.tionand for gasifying the carbonizecl product I which comprisesblasting air through an incandescent fuel bed to form highly heatedblast gasses, passing said gases in indirect heat exchangerelation witha column of rfuel of annular cross section above but out of contact withsaid fuel bed While dividing the volume of the said t 'l as to passpredetermined' proportions thereof re-l highly heated gases so as topass predetermined proportions thereof respectively adjacent the innerand outer surfaces of the annular column, and subsequentlydischargingthe carbonizedfuel onto the said fuel bed. l

8. The processas defined in claim 7 including the step of burningpredetermined portions of the .said blast gases at selected pointsadjacent to the outer surface of the annular fuel column Ato indirectlyheat the portions of the fuel remote from the said incandescent fuel bedto substantially the sameA temperature as that portion of the fuelcolumn nearest to the said bed. y

9.,'Ifhe semi-continuous process for concurrently carbonizing andgasifying fuel which comprises blasting air through an incandescentfuelbed and passing the resultant highly heated blast gases in indirectheatexchange relationship with at least one column of fuel of relativelythin annular cross section, 'thereafter n passing steam through the saidfuel bed and passing the result-V ant highly heated water gas inindirect heat exchange relation with the 4fuel being carbonized, thelovverl part of the fuel column being subjected to a higher temperaturethan the upper part of the said solumn in each ofthe said heatexchangesteps, and thereafter passing superheatedsteam in indirect heat exchangerelation With the column of fuel rbeing carbonized in the directionoposite to the flow of the said heating gases along the'said column foreffecting a uniform carbonizat-ion throughout the length of the fuelcolumn, and discharging the carbonized fuel onto the incandescent fuelbed for use in a subsequent gasification step and for supplying heat forcarbonizing subsequent charges of fuel.

. which comprises blasting air through an incan- 'descent fuel bed toform highly heated blast gases,

passing the said gases in indirect heat exchange relation with the innerand outer surfaces of a column of fuel of annular cross section abovebut out of contact with said fuel bed While dividing the volume of thesaid highly heated gases so spectively along the inner and outersurfaces of the anular column, and adjusting the rate of flow of heat tothe said inner surface of the fuel column throughout the carbonizationby heat storage and heat transmitting bodies. K

11. The process ofconcurrently producing a combustible gas and ofcarbonizing solid fuel which comprises successively passing air andsteam through an incandescent fuel bed while dividingV and passingportions of the 'resultant highly-heated combustible gases along and inindirect heat exchange relationship respectively with each of thelateral surfaces of a column of fuel arranged in a thin annularlayerabove the -said fuel bed, -thereafter passing superheated Ysteam alongand in indirect heat exchange relationship with the said column of fuelin` a direction opposite to the direction of flow of the aforesaidhighly heated combustible gases, then passing the said superheated steamthrough the fuel bed to produce a combustible gas,radiating heat to thesaid fuel column from the incandescent fuel bed during each of the abovesteps,

recovering the various combustible gases produced, and discharging thecarbonized fuel onto the said fuel bed.

12. The process as defined in claim 11 in which the effective heattransferred to the fuel column by the said combustible gases andsuperheated steam is in the range of from 105()D F. to 1500 F.

13. The process as defined ingclaim 1l in which .the saidcolumn of fuelbeing carbonized is in a.

thin annular layer havingk a mean thickness of from 11/2 inchesto 5inches. e

14. The process of distilling and gasifying solid fuel disposed in athinstationary layer, which comprises passing a combustion-supportingfluid through an incandescent fuel bed, and concurrently passingregulated portions of the resultant highly-heated combustible gases inindirect heat exchange relation respectively along both -the outer andinner surfaces of a column of fuel arranged in a thin annular layeradjacent to but `out of contact with the saidfuel bed, the said hotgases serving to supply at least a portion of the heat for uniformlycarbonizing the said fuel.

15. The process of concurrently producinga combustible gas and ofcarbonizing solid fuel, which comprises passing air throughanincanvdescent fuel bed, dividing and passing regulated portions oftheresultant highly-heated combustible gas along and in indirect heatexchange relation with the respective inner and outer surfaces of acolumn of fuel disposed in a thin annular layer above the said fuel bed,burning a selected portion of the said combustible gasvduring suchpassage and utilizing heat produced thereby for carbonizing the saidfuel, carbureting another portion of the said combustible gas, utilizingpotential and sensible heat of the first-named portion of thecombustible gasfor `supporting the carburetion of the last-named portionof the said gas, and recovering thecarbureted combustible gas.

16. The process of concurrently producing a combustible gas and ofcarbonizing `solid fuel, which comprises passing air through anincandescent fuel bed, dividing and passing regulated portions of theresultant highly-heated combustible gas along and in indirectheat-exchange relation with the respective surfaces of a column of fuelVdisposed in a. thin annular layer above the said fuel bed, burningy aselected portion of the said combustible gas during such passage andutilizing heat produced thereby for carbonizing the said fuel,carbureting another portion of the said combustiblel gas, utilizingpotential and sensible heat of the first-named portion of thecombustible gas for supporting the carburetion `of the last-namedportion of the said gas, recovering thev carbureted combustible` gas,thereafter passing superheated steam along and in indirect in adirection opposite tothe directionyofiiovw of the first-namedcombustible gas, then passing the said superheated steam through thefuel bed to produce a second combustible gas, recovering the latter, andradiating carbonizing heat to the said fuel column from the incandescentfuel bed during the respective steps of passing air and steam in thesaid heat-exchange relation with the fuel column.

17. The process of concurrently producing a combustible gas and ofcarbonizing solid fuel, which comprises passing air through anincandescent fuel bed, dividing and passing regulated portions of theresultant highly-heated combustible gas along and in indirectheat-exchange relation respectively with each of the surfaces of acolumn of fuel disposed in a thin annular layer above the said fuel bed,thereafter passing steam through the fuel bed, thereby producing asecond combustible gas, dividing the last-named combustible gas andpassing regulated portions thereof along and in indirect heat-exchangerelation with the respective surfaces of-the annular fuel column, thencarbureting a selected portion of the last-named combustible gas andsupporting the said carburetion by heat regenerated in the process,passing superheated steam in indirect heat-exchange relation With thesaid fuel column in a direction opposite to the flow of the lastnamedcombustible gas, and then passing the superheated steam through the fuelbed to produce a third combustible gas, and recovering the variouscombustible gases produced during the respective steam treatments.

18. The process of concurrently producing a combustible gas and ofcarbonizing solid fuel,

which comprises successively passing air andv steam through anincandescent fuel bed While dividing and passing regulated portions ofthe resultant highly-heated combustible gases upvsubsequent carburetionof the combustible. gases produced in the process, thereafter passingsuperheated steam downwardly along and in indirect heat-exchangerelation With the said co1- umn of fuel and thence through the fuel bedto produce a combustible gas, carbureting the respective combustiblegases produced during the steam treatments, recovering the same, andperiodically discharging the carbonized fuel upon the said fuel bed. i

19. The semi-continuous process for distilling and gasifying solid fuelin which the latter during distillation thereof is disposed in a columnof thin annular cross-section, which comprises 100 heating a column ofthe solid fuel to be carbonized, While disposed in a thin annular layer,by means of hot gases moving longitudinally of and in indirect heatexchange relation with the said column through each surface of the saidlayer, and burning controlled amounts of the said hot gases at selectedpoints spaced length- Wise of and adjacent the fuel column in suchmanner as to control the temperature of the fuel at such points in thecolumn irrespective of the relative distance of these points from thesource of the said hot gases.

ALFRED JOHNSON.

